Abstract:

Objective To investigate the effect of eucalyptus oil with retinoic acid on the expression of paired box3(Pax3)and connexin (Cx43) in the fetal rat brain tissue.Methods Forty-two pregnant SD rats were randomly divided into 6 groups (7 rats per group), normal group，retinoic acid group (RA), solvent group (peanut oil +RA) and 3 experimental groups (according to eucalyptus oil of high, medium, low dose +RA), normal group with free diet. RA group lavaged with retinoic acid (40 mg/kg) at gestation 10th day. Three experiment groups and solvent group were lavaged from the 7th to 14th day with eucalyptus oil in 300 mg/kg, 200 mg/kg, and 100 mg/kg and peanut oil 2ml per animal per day, respectively. Each of them was lavaged with retinoic acid (40mg/kg) at gestation 10th day. All pregnant rats were sacrificed at the 21st day and the live-fetus was collected. Expression of Pax3, Cx43 protein and it's mRNA in fetal rat brain tissue were detected by Western blotting,immunohistochemistry and Real-time PCR. The vertebrae development and paravertebral space of fetus were observed under a stereoscope by staining with alician blue and alizarin red S. Results The number of fetal rats with abnormal vertebrae in lavaged retinoic acid groups were not significantly different from those in normal group, but the lowest percentage of vertebrae form abnormal (55%, eucalyptus 300 mg/kg +RA 40mg/kg) and vertebrae the division(45.8% eucalyptus 100 mg/kg +RA40mg/kg ) were higher than those in normal group(0,0) (P<0.05). In lavaged retinoic acid groups, the highest percentage of vertebrae form abnormal(62.5%, eucalyptus 100 mg/kg +RA 40mg/kg) or vertebrae the division(55.5% eucalyptus 300 mg/kg +RA40mg/kg ) of fetal rats in eucalyptus oil groups were lower than those in retinoic acid group(73.7%,73.7%) and solvent control group(68.2%,63.6%), (P<0.05). Compared with normal group, the expression of brain tissue Pax3、Cx43 protein and mRNA in graged retinoic acid groups were significantly higher than those in normal group (P<0.05). In lavaged retinoic acid groups, the expression of fetal brain tissue Pax3, Cx43 protein and mRNA in intragastric eucalyptus oil groups were significantly lower than those in pure graged retinoic acid group (P<0.05). Conclusion Eucalyptus oil can antagonize the neural tube defects caused by RA. Its mechanism may be related to eucalyptus oil antagonize Pax3 and Cx43 protein overexpression which caused by RA.

Key words: Eucalyptus oil, Retinoic acid, Neural tube defects, Paired box 3, Connexin 43, Immunohistochemistry, Western blotting, Real-time PCR, Rat